Screwdriver with gripping arrangement for holding the screws



J. LUNDMAHK. SCREWDRIVEH WITH GRIPPING ARRANGEMENT FOR HOLDING THE SCREWS.

APPLlCATION FILED mm.- 8. 1919.

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SCBEWDRIVER WITH'GRIPPING ARRANGEMENT FOR HOLDING THE-SCREWS. APPLICATION nuzn MAR. B. 1919.-

1,399,635. Patented 6, 1921.

In]; ezz/z JTlhancLmwz-A: jy a UNITED STATES PATENT OFFICE.

J'OI-IANNES IlIJJ'NDlvLZlLRK, 0F ASKIM, SWEDEN, ASSIGNOR TO LANIA NAVIGATIONS- INSTRUMENT AKTIEBOLAG, 0F GOTTENBORG, SNEDEN'.

sonnwnnrvnn wrrir enrrrnve ARRANGEMENT FOR HOLDING THE sonnws.

Specification of Letters Patent.

Patented Dec. 6, 1921.

Application filed March 8, 1919. Serial No. 281,471.

To all whom it may concern.

Be it known that I, J OHANNEs L'UNDMARK, a subject of the King of Sweden, residing at Aslrini, in the county oi 'Goteborg and Bohus and Kingdom of Sweden, have invented new and useful Improvements in Screwdrivers with Gripping Arrangements for Holding the @crews, of which the following is a specification.

This invention relates to screw'drivers fitted with a gripping-device having for its object to facilitate the driving of woodscrews or other screws, the heads of which are provided with a slot for the screw driver.

This gripping device is provided to hold the head of the screw tightly against the end of the screwdriver and thus to lreep the screw steady, while its point is being pressed into the material, into which the screw is to be driven; My invention has for its object to improve such devices as previously known. One of its objects is to provide a device for grasping the head of the screw with great steadiness,sothat also screws of extraordinary length may conveniently be handled. The invention is characterized mainly bya flexible guard, provided to be pushed along the screw-driver, thereby acting upon a pair of jaws provided for gripping the head of the screw and for holding it securely against the end of the driver, so as to prevent the screw from collapsing while being driven, even if the screw should require to be pressed violently during this operation. in the annexed drawings two somewhat different embodiments of this invention are illustrated, oneoi these embodiments being shown in Figures 1, 2, 3, t, and the other in .Figsj5, 6, 7, 8. j j

Fig. 1 represents aside-view of a screwdriver with its gripping device in section and shown in open position. j j I Fig. 2 shows the sameparts in closed position. i

Fig. 3 shows the same parts in inoperative position. j

Fig. t shows an end-view of the screwdriverlheld with its end directed against the observer.

F 5 shows a side-view o'l theother em bodinient with its gripping device partly in section and with a screw clenched between the jaws.

Figs. 6 and 7 represent sections of the principal parts of the gripping device in difterent operating positions.

F 1g. 8 shows the screw-driver in operating condition and partly in section viewed from another direction as compared to Figs. 5, 6 and 7.

The embodiment shown in Figs. 1-4 pre sents a screw-driver provided with a flange 2,] against which the spiral-spring 3 is supported. This. spiral-spring incloses the stem of the driver 1, and its opposite end is supported against the rear part of the V-shaped guard 4, the prongs of which are held together at their outer ends by means of a pin 5 passing through an oblong hole 6 in the driver and also through similar holes 7 in two jaws 8 slidably attached to the driver and bent inward just about their middle portion. The pin 9 fixed to the guard at is somewhat bent and penetrates through the holes 7 in the jaws 8. These jaws are riveted to a V-shaped fiatspring 11 (only the heads 10 of the rivets are shown in the illustration). The spring 11 endeavors to separate the outer ends of the jaws 8 from one another; these ends being bent inward and of such a shape, that they are capable jointly to grasp the screw 12, which is to be driven, in such a manneigthat the slot in the screw-head is held securely pressed against the end ofthe driver (see Fig. The jaws 8 are substantially straight compleinental sections joined at their inner ends which are slightly curved by a flat spring 11 having an opening 23 through the medial portion thereof. The driver 1 is arranged through this opening and between the jaws as indicated.

in order to guide the end of the driver, 7

vided 0n the pin 5 on each side of the'driver.

The device operates as follows:

When the jaws 8 are in the position shown by Fig. 8, they are held back upon the driver 1 thus leaving its end free, so as to allow the tool of being used as an ordinary screw-driver. When a screw is to be gripped,the guard 4c is shoved toward the end of the. driver against the pressure of the spiral-spring 3 causing the pin 5 to come into contact with the outer edges of the holes 7 and to shove the jaws 8 along the driver toward its end until they come into the position shown in Fig. 1., The jaws are now held open by means of the flat '8 together with the screw 12 to the spring 11, so that the head of the screw 12 can be passed between their ends, while the end of the driver is held in position to enter the slot 13 in the screw. When the guard at is let loose, the spiral spring 3 will shove it backward along the stem of the screw-driver, which causes the pin 9 to come into contact with the inner edges of the holes '7 and to withdraw the jaws position shown in Fig. 2, so that the edge of the driver is inserted into the slot 13 and firmly pressed against 2 the head of the screw, which thus becomes securely v and steadily held and may enter and be driven into the object 22 without any hole being previously bored. During this operation the screw-drivercannot slip out of the slot 13 of the importance'when driving screws into fragile' objects-forinstance pieces of fiurni-Z tur'e, &'c.-which otherwise might be damaged through the slipping of the screwdriver. lVhen the screw 12 has become driven into contact with the surface ofsaid object, thejaws areautomatically forced to open and are immediately brought back by means of the spiral-spring 3 into the position shown in Fig. 3.

The embodiment of the invention illustrated by Figs. 5-8 is distinguished from the device described above by the following features. V

i The jaws 8 'as'shown in Fig. 5 are provided on their inner surfaces with a plurality of pairs of opposed projections for holding the shank and, head of the screw 12'. V In the present embodiment only two pairs of opposed projections are illustrated, the inner pair being adapted to first receive the head of the screw when the latter is inserted in the driver while the outer pair engage theshank preferably at a point medially of thelength of the screw simultaneously with the gripping of the head by the inner notches. It is thus apparent I that the screw is gripped and held at two a driver when in position in while 1t-1s belng drlven into substantially widely spaced points'so that it is securely and steadily held toprevent itfrom wabbling with respect to the screwthe screw-driver an anchored position. This is of. particular importance in the case of;rather long screws.

When the driving of the screw has proceeded approximately half of the length of the screw, the end of the jaws come into contact with thesur'face of the object or work intowhichthe screw is being driven and the pair of projections between which thescrewis held'loosen their hold automatically and slip over the screw head while that portion of the shank adjacent the head is immediately gripped by the outermost pair of opposed projections which maintain screw 12, which is of a particulartheir hold until they slip from the screw head at the time the screw is completely driven into the object by the tool. It is of course apparent that in the case of exceptionally long screws that additional pairs of opposed inner projections may be pro vided on the inner faces of the jaws which incidentally may be slightly elongated.

In the embodiment disclosed in Figs. 5 and 8 the jaws are provided with two pairs of opposed notches forming two pairs of projections 15 and 16 are formed. On the outside of the jaws 8 there are formed projections 18 and inclined surfaces, against which the bent prongs of the guard 4; are pressed by the action of the spiral spring 3. Thus the said jaws are clenched together against the action of the U-shaped spring 11. This spring 11 is attached to the jaws 8 by means of rivets 24, and endeavors to hold the said jaws apart from one another and from the driver 1. The portion 19 of the spring 11 being bent inward keeps in touch with the driver 1 and thus holds the jaws 8 in different positions relative to the driver on account of the pressure and friction exercised against the sides of the driver. The guard 4 is provided with a plate 21 projecting from that end of the guard, which is turned toward the handle of the tool. By pressing his thumb against this plate 21 the operator is able to shove the guard 41: outward in the direction of the end of the driver, so that the pin 5 attached to the guard is brought into contact with the outer end of the slot 7 in the jaws 8 thus carrying these jaws along with the guard at and bringing them into position for gripping the screw 12.

his device operates mainly in the same way as that described above. When a screw 12 is to be gripped, the guard 4 is shoved outward by pressing against the plate 2!. Thus the ends of the jaws 8 are projected in front of the end of the driver and are separated by the action of the spring 11, whereupon the screw 12 is fixed as shown in Fig. 5 with its slot 13 in front of the driver end. On account of the pressure from the spring 11 against the side of the driver 1 the displacement of the jaws 8 in the direction toward the driver end is prevented, until the guard 4 is shoved forward so far, that the pin 5 comes into contact with the upper edge of the hole 7; the continued movement of the guard 41 then causes the jaws 8 to follow. The result of this combined motion is, that'the ends of the guard 4 first are able to slide forward down the inclined surfaces 17, and thus do not prevent the separation of the jaws 8 by the pressure of the spring 11. The operator then releases the guard 41, which immediately will be shoved backward by the spiral-spring 3, and the extremities of the guard will press against the inclined surfaces 17 of the projections 18 thus clenching the jaws 8 to gether, so that their ends 15 will grip the stem of the screw, and at the same time the inner notches 16 will grip the head of the screw. When the screw is driven into the object 22 to such a depth, that the jaws touch the surface of the object 22 with their ends, the jaws will be forced apart through the pressure of the inclined surfaces of the notches 16 against the conical surface of the screw-head, and ultimately these notches will slip-over the screw-head. This will now be gripped by the notches 15, as shown in Fig. 6, and at the sanietime the pin 9 will come into contact with the inner edge of the hole 7 the extremities of the guard 1- pressing against the inclined surfaces 17 of the projections 18 will cause the jaws 8 to be withdrawn out of contact with the surface of the object 22, thus allowing the screw-head to be gripped by the notches 15. The driving of the screw being continued, the ends of the jaws 8 will once again come into touch with the surface of the object 22, and the pressure of the notches 15 against the conical surface of the screw-head will again force the jaws apart, the notches will slip over the screw-head, as shown in Fig. 7 and loose their grip of the screw, the jaws will be withdrawn behind the end ofthe driver, and'the screw may be driven completely into the object 22.

Slight modifications in the device as mentioned may of course be made without changing the leading principle of this invention. For instance the guard 1 may be devised in such a manner, that the aws 8 will open. by pulling the guard 4: backward from instead of shoving it toward the end of the driver. In place of the spring 11 other devices may be provided for holding the jaws in place, so that they will not be carried along with the guard l, until the edges of the holes in the jaws come into contact with the pin 5.

Having thus particularly described and ascertained the nature of my said invention, and in what manner the same is to be performed, I declare that what I claim is:

1. In screw-drivers the combination of a gripping-device consisting of two jaws flexibly connected to one another and slidable along the driver to hold the screw to be operated securely against the end of the driver, an adjustable guard slidable along the driver and along the jaws and pressed against the outer sides of the jaws, the said guard being spring-actuated, so as to strive to shove itself backward from the end of the driver, and also being provided with a member connecting the guard with the jaws, so that these are caused to be carried along with the guard and thereby clenched about the screw to be operated.

2. A screw-driver as claimed in claim 1 wherein the jaws on their inner surface are provided with a plurality of pairs of opposed projections, each of these projections being of a length at least equal to half the difference between the diameter of the head of the screw actuated upon and the diameter of the stem of the said screw proper so as to form supports at substantially widely spaced points, the inner pair of projections being provided to grip the head of the screw during the first stage of the screwing motion and the outer pair of projections being adapted to simultaneously grip the stem of the screw at a point suitably apart from the head, the ends of the jaws having a substantially smooth surface so as to permit the jaws to open up themselves automatically to make the head of the screw slip off a pair of projections when the said ends become forced against the object into which the screw is drawn.

2-3. A screwdriver as claimed in claim 1 wherein the guard is connected to the jaws means of two pins fixed in the prongs of the guard and passing through oblong holes bored lengthwise in the driver 1 and in the jaws, these holes being caused to cotiperate with the said pins in such a manner, that the guard and the jaws are properly guided and regulated in their movements.

4. A screw-driver as claimed in claim 3 wherein the jaws are connected by means of a spring exerting a certain pressure against the driver 1, so that a certain force is required to move the jaws along the driver, and furthermore, that the one pin is provided to carry the jaws along with the guard, when it is shoved in the direction toward the driver end, and the other pin is provided to move the said jaws with the guard, when it is shoved backward in the direction toward the handle of the tool.

5. A screw-driver as claimed in claim 1 wherein the movable guard is provided at its inner end with a pressing plate, by means of which the guard may be moved in an outward direction with the thumb of theoperator thus carrying the jaws forward in order to make them grip the screw.

6. A screw-driver as claimed in claim 1, wherein one of the pins is provided with two knobs or flanges for guiding the driver.

In testimony whereof I have affixed my signature in presence of two witnesses.

JOHANNES LUNDMARK.

Vi itnesses ALroNs Hnnnnne, E. ANnnnAsoN. 

